A process has been heretofore applied to a patient who is difficult to take nutrients from the mouth in which an enteral nutrient is infused to the patient through a catheter inserted from the mouth and the nose. Specifically, the enteral nutrient stored in its bag or bottle is infused in the body of the patient through an infusion set or a catheter. The enteral nutrient is prepared by adding water or warm water to a concentrated liquid or powdery enteral nutrient. After prepared in another vessel the prepared enteral nutrient is poured from the vessel into a bag or bottle for enteral nutrient. Alternatively, the enteral nutrient is directly prepared in a bag or bottle for enteral nutrient. However, the method wherein the prepared enteral nutrient is poured into the bag or bottle after prepared in another vessel involves a trouble that the use of another clean vessel is needed and further has the disadvantage that there is a high risk of mixing a dust or the like therein. A method of preparing the enteral nutrient directly in a bag is disclosed in, for example Japanese Patent Application Laid-Open No. Sho 57-86275. The bag disclosed therein is a bag container stored a solid or liquid substance which is dispersible or dissoluble in a liquid, said bag container having a resealable liquid inlet. There are disclosed in the example thereof a liquid inlet composed of a zipper, the outer part of the zipper being further provided with a heat seal part and the heat seal part to be cut off by scissors for use, etc. However, the bag container having the liquid inlet composed of a zipper alone has the disadvantages in that it has a poor sealing property so that it adversely affects on the quality of the enteral nutrient stored therein, and it is difficult in the virgin proof (tamper proof). Also, the bag container wherein the outer part of the zipper is provided with the heat seal part has a defect that the operation efficiency is bad because scissors must be used.
So, one of the present applicants proposed already a liquid storage bag as shown in Japanese Patent Application Laid-Open No. Hei 11-285518 as one of solving the disadvantages as stated above. In the bag, as shown in FIG. 2, the upper part thereof is closed with a freely openable and closable closing means, the bottom thereof is provided with a liquid exit, the internal space thereof is divided liquid-tightly into upper and lower parts through an easily peelable partition wall which is provided close to the closing means, and liquid is stored in the divided lower internal space. However, this bag has the disadvantage that when the width of the partition wall is made small, the partition wall may peel off by an accidental drop thereof, etc. while when the width of the partition plate is made large, it is hard to peel off, and hence some improvements were still needed for the bag.